Western Brown Snakes (nuchalis-complex)

Western Brown Snakes (*nuchalis-complex*) are a cryptic species including at least 3 distinct species erroneously classified under *Pseudonaja nuchalis*. The complex includes the Gwardar (*Pseudonaja nuchalis*), the Strap-snouted Brown Snake (*Pseudonaja aspidorhyncha*), and the Mengden's Brown Snake (*Pseudonaja mengdeni*). Other species may exist. Each of these species may be collectively referred to as the Western Brown Snake.

The Gwardar (*Pseudonaja nuchalis*), is a medium species (typical length 1.5m) of highly venomous snake in the family Elapidae, native to Australia, and found in Tropical NT, north of 17°S. It is a long and slender snake, with a smallish head indistinct from the neck. When viewed from above the snout most often has a chisel-shaped appearance. Scales are smooth and semi-glossy. Dorsal colour light to medium brown on the body, with the head and neck sometimes dark brown or black and the snout being paler than the head. Occasionally there is a series of faint to obvious broad dark brown bands along the body, and scattered dark brown or black scales on the neck. The belly is cream or pale yellow, often with salmon blotches (particularly on the anterior section); chin is cream coloured. The eye is large with a dark iris and an orange ring around the pupil. The inside of the mouth is blackish.

The Strap-snouted Brown Snake (*Pseudonaja aspidorhyncha*) is a medium species (typical length 1.5m) of highly venomous snake in the family Elipidae, native to Southern central Australia, south of 27°S, from Penong, western Eyre Peninsula, South Australia, eastwards to Hermidale, central New South Wales. It is a long and slender snake, with a smallish head indistinct from the neck. When viewed from above the snout has a chisel-shaped appearance. Scales are smooth and semi-glossy, often very glossy around the head and neck. Dorsal colour and pattern is highly variable; the base colour ranges from pale to medium brown on the body, with the head often darker brown. While some individuals may be unpatterned, there is usually a degree of dark banding present which is often more pronounced along the sides and posterior half of the body. These bands can be one to many scales wide and range from very faint to quite distinct. Broad bands are occasionally interspersed with a number of narrower bands. A dark band on the neck is often present, and there may also be a scattering of dark brown or black scales on the head and neck. The belly is dirty-cream, yellow or medium brown, becoming paler under the throat and chin. The eye is large with a dark iris and a reddish-orange ring around the pupil. The inside of the mouth is dull pinkish-grey.

The Mengden's Brown Snake (*Pseudonaja mengdeni*) is a medium species (typical length 1.5m) of highly venomous snake in the family Elipidae, native to Western and central Australia, from Carnarvon, Western Australia, to Mootwingee National Park, western New South Wales. It is a long and slender snake, with a smallish head indistinct from the neck. When viewed from above the snout has a rounded appearance. Scales are smooth and semi-glossy, often very glossy around the head and neck. Dorsal colour and pattern is variable but almost always conforms to one of two distinct forms; the *Orange with black head* or *Pale head, grey nape* morph.

- *Orange with black head* - base colour ranges from pale to dark yellow or orange on the body, with the head and neck being dark brown or black. The body typically has a fine to heavy black reticulated pattern, which is often absent anteriorly. Sometimes there may also be a series of broad, dark brown bands down the length of the body. The belly is cream or yellow, and is often blotched with orange, salmon, dark brown or grey. Chin and throat cream, dark grey or black. The eye is large with a dark iris and a reddish-orange ring around the pupil. The inside of the mouth is blackish.

- *Pale head, grey nape* - base colour ranges from pale to medium brown or yellowish, with the head and neck pale to light brown. The body typically has a fine reticulated pattern, which is often absent anteriorly. An indistinct pattern of thin greyish brown bands can be present (more obvious on the sides and towards the back half). Some specimens may exhibit a pattern of broad dark brown bands interspersed with narrower bands. Typically there is a broad darker brown or greyish brown band on the neck, often bordered anteriorly by several black scales (sometimes forming a ‘V’ or ‘W’ shape). The belly is cream or yellow, and is often blotched with orange, salmon, dark brown or grey. Chin colour is cream. The eye is large with a dark iris and a reddish-orange ring around the pupil. The inside of the mouth is blackish.

Western Brown Snakes overlap in distribution with a number of other snakes that are similar in appearance, particularly other species of brown snake (*Pseudonaja spp.*). Close examination is often necessary to make a positive identification. Within the Western Brown Snakes *Pseudonaja aspidorhyncha* may be differentiated from *Pseudonaja mengdeni* and *P. nuchalis* by its lighter coloured mouth (blackish in both mengdeni and nuchalis). The most easily-observed difference between *mengdeni* and *nuchalis* is that the rostral scale in *nuchalis* is long and strap-like, and the snout appears squared-off from above, whereas in *mengdeni* the rostral is not particularly elongated and the snout is more rounded.

Western Brown Snakes may also be confused with another large brownish-coloured snake, the unrelated Mulga Snake (*Pseudechis australis*), however Mulga Snakes tend to have a broader head and “heavier” build (particularly larger specimens), and never show any sort of banded pattern.